1. Field of the Invention
This invention relates to a liquid crystal element using a film transistor as a switching element.
2. Description of the Prior Art
The liquid crystal element of the type as described heretofore known has a construction as shown in FIGS. 4 and 5. A liquid crystal element is indicated generally at 1. In this liquid crystal element 1, a liquid crystal 4 is poured into a gap formed between a lower substrate 2 and an upper substrate 3 opposed to each other, the liquid crystal 4 being sealed in a liquid-tight manner by a sealer 5 disposed in the peripheral edges of the substrates 2 and 3.
The lower substrate 2 is formed slightly larger than the upper substrate 3. On the opposed surface (upper surface in the figure) of the lower substrate 2 is provided a film transistor (hereinafter referred to as TFT) as a switching element internally of a portion surrounded by the sealer 5, and a picture element electrode 7 formed of such as ITO in the form of a film is formed adjacent to the TFT 6. The lower substrate 2 is provided with a spacer (not shown) for maintaining constant a cell gap between the lower substrate 2 and the upper substrate 3.
On the other hand, on the opposed surface (lower surface in the figure) of the upper substrate 3 is formed a transparent electrode 8 formed of ITO or the like in the form of a film internally of a portion surrounded by the sealer 5.
In the liquid crystal element 1 constructed as described above, in the past, a conductive path adapted to provide electric communication between the transparent electrode 8 and outside the element is formed from a silver paste. To form the conductive path, a web-like metal film 9 formed of chrome or the like is first formed on the upper surface of the lower substrate by film forming methods such as spatter method, metal vaporization method and the like. In this case, the metal film 9 is formed from the peripheral edge of the lower substrate 2 to the inner part of the lower substrate 2. On end 9a of the peripheral edge of the lower substrate 2 is formed as a terminal for removing an external portion of the transparent electrode 8, whereas the other end 9b thereof is formed so as to be extended toward the inside of a portion surrounded by the sealer 5. Then, the silver paste is coated on the other end 9b of the metal film 9 to form a conductive portion 10. Next, the upper substrate 3 is superposed to the lower substrate 2 to bring the conductive portion into contact with the edge of the transparent electrode 8 of the upper substrate 3, after which a gap between the lower substrate 2 and the upper substrate 3 is closed by the sealer 5 to provide a cell construction.
In the liquid crystal element 1 as described above, the transparent electrode 8, the conductive portion 10 and the metal film 9 are electrically connected, and the metal film 9 and the conductive portion 10 constitute a conductive path of the transparent electrode 8.
However, in the liquid crystal element 1 as described above, there are required many steps of preparing the conductive path of the transparent electrode 8, posing a problem which requires much labor for the manufacture.